For the 1960 season, combustion chambers were reworked for G80, G80CS and 500/650 twins. For 1964, the G80CS cylinder head was reworked again (026702 -> 031623). I have seen pictures of the later one - there are some changes to the casting in the spark plug area - but what are the finer points? The late number indicates this was a modification made for the G85CS works machines at first. Was the firing slot finally abandoned and a 10mm plug fitted?

Different Marty. You are after the Australian, not the Kiwi. As an aside, I attended the Oz Jampot at Boonah, Qld. Met Marty and his problem children. I think he is very close to having both sorted, or as close as one can.

Marty wrote:Different Marty. You are after the Australian, not the Kiwi. As an aside, I attended the Oz Jampot at Boonah, Qld. Met Marty and his problem children. I think he is very close to having both sorted, or as close as one can.

Of course it is, sorry I should have realised by the way you're still beating that bloody animal!!!!